[llvm] r336010 - [LLVMContext] Detecting leaked instructions with metadata

[Vedant Kumar via llvm-commits]

Author: vedantk
Date: Fri Jun 29 13:13:13 2018
New Revision: 336010

URL: http://llvm.org/viewvc/llvm-project?rev=336010&view=rev
Log:
[LLVMContext] Detecting leaked instructions with metadata

When instructions with metadata are accidentally leaked, the result is a
difficult-to-find memory corruption in ~LLVMContextImpl that leads to
random crashes.

Patch by Arvīds Kokins!

Modified:
    llvm/trunk/lib/IR/LLVMContextImpl.cpp

Modified: llvm/trunk/lib/IR/LLVMContextImpl.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/LLVMContextImpl.cpp?rev=336010&r1=336009&r2=336010&view=diff
==============================================================================
--- llvm/trunk/lib/IR/LLVMContextImpl.cpp (original)
+++ llvm/trunk/lib/IR/LLVMContextImpl.cpp Fri Jun 29 13:13:13 2018
@@ -48,6 +48,14 @@ LLVMContextImpl::~LLVMContextImpl() {
   while (!OwnedModules.empty())
     delete *OwnedModules.begin();
 
+#ifndef NDEBUG
+  // Check for metadata references from leaked Instructions.
+  for (auto &Pair : InstructionMetadata)
+    Pair.first->dump();
+  assert(InstructionMetadata.empty() &&
+         "Instructions with metadata have been leaked");
+#endif
+
   // Drop references for MDNodes.  Do this before Values get deleted to avoid
   // unnecessary RAUW when nodes are still unresolved.
   for (auto *I : DistinctMDNodes)